A Unified Control System with Autonomous Collision-Free and Trajectory-Tracking Abilities for Unmanned Surface Vessels Under Effects of Modeling Certainties and Ocean Environmental Disturbances

A unified control system that possesses the abilities to arrange collision-free trajectories, precise trajectory tracking, and control allocation for unmanned surface vessels is investigated in this paper by integrating methods, including an image-based trajectory generator, a nonlinear robust controller, and a control allocation maker. For the purpose of rapidly generating an optimal collision-free trajectory, a rapid image-searching method, named double-sided Finite Angle A* (FAA*), is developed to cooperate with a continuous trajectory generator. This proposed control system provides an effective means for letting controlled unmanned surface vessels be able to execute given tasks by following collision-free trajectories under the influences of modeling uncertainties and ocean environmental disturbances. To eliminate the effects of modeling uncertainties and ocean environmental disturbances, a robust compensator is developed to co-work with a nonlinear control law. Furthermore, the required robust control commands are perfectly performed by a pair of rotatable actuators with an analytical control allocation design. Finally, two demonstrations are examined to validate the control performance of this proposed unified control system.